Thousands of mourners gathered in Moscow for the funeral of Russian opposition leader Alexey Navalny despite a heavy police presence and the threat of detention.

Mourners clapped and chanted Navalny’s name as his coffin arrived at the church where his funeral took place. Others shouted “Putin is a killer” or “no to war.”

Navalny, Russian President Vladimir Putin’s most formidable opponent, died aged 47 in an Arctic prison on February 16, sparking condemnation from world leaders and accusations from his aides that he had been murdered. The Kremlin has denied any involvement in his death.

Navalny’s team encountered difficulty in retrieving his body from Russian authorities and hiring a venue for his funeral, which was held Friday afternoon at the Church of the Icon of the Mother of God in Moscow’s Maryino district, where the Kremlin critic lived.

He was later buried at Borisov Cemetery, where Frank Sinatra’s “My Way” played as his coffin was lowered into the ground. A system was in place to allow mourners to pay their respects to Navalny at the burial site.

Crowd control barriers were erected along the route to the cemetery, flanked by dozens of police vans. Police officers were deployed on rooftops overlooking the growing line of mourners, video from the scene showed.

Ahead of the funeral, Kremlin spokesperson Dmitry Peskov warned Russians against unauthorized memorials for Navalny, saying those attending would be “in violation of the law.”

Maria Pevchikh, a close aide to Navalny, said the chants for Navalny will continue. “People are chanting ‘Navalny! Navalny!’ in loud voices. This chanting we will hear in months’ time, in a year’s time,” she said.

Around 20 minutes before Navalny’s funeral began, the live signal of the CNN team on the ground appeared to be blocked. The live feed organized by Navalny’s team also dropped. CNN’s signal went back up shortly after the service finished.

A Russian woman named Polina, one of thousands of mourners outside the church, told CNN’s Matthew Chance that Navalny’s death was “horribly sad,” but that it had united many Russians.

“There are obviously some people who are, I guess, against the whole thing that is happening right now. I can’t say it, obviously. But there are some people who have good hearts.”

Dissent has been effectively outlawed in Russia since Putin launched the full-scale invasion of Ukraine more than two years ago. Russian authorities outlawed Navalny’s movement as extremist and expressing support for him can be perilous.

Navalny’s team shared an image from inside the church during the service, showing the Kremlin critic’s body showered with roses while his mother, Lyudmila Navalnaya – who spent more than a week in Siberia attempting to retrieve her son’s body – held a candle and watched on.

Those waiting in line ahead of the service told CNN they had gathered to pay their respects to their “hero.” Marina said she had traveled from St. Petersburg because she “loved” Navalny.

“He was a true hero … I want to say to him ‘farewell,’” she said, adding that she was not surprised that the Kremlin had denied any involvement in Navalny’s death. “They demonstrate to the whole world we do what we want to do,” she said. “We can repress you.”

Another woman, Tatiana, 82, said she had attended several of Navalny’s meetings and was a longstanding supporter.

“I always supported their [Navalny’s] policy, their ideas. I share these ideas,” Tatiana said.

Neither woman said they were deterred by the potential risk of coming to the funeral.

But Yulia Navalnaya, Navalny’s widow, had said ahead of the funeral that she is concerned police will crack down on mourners.

“I’m not sure yet whether it will be peaceful or whether police will arrest those who have come to say goodbye to my husband,” she told the European Parliament on Wednesday.

At least 45 people were arrested across Russia on Friday for paying their respects to Navalny, monitoring group OVD Info reported. It said six people were detained in Moscow, while 18 were detained in the Siberian city of Novosibirsk – the largest number of any city. Another 10 were detained in Yekaterinburg for laying flowers. CNN could not independently verify the report.

Navalnaya, now living in exile along with their children most of Navalny’s team, thanked her husband for “26 years of absolute happiness.”

“I don’t know how to live without you, but I will try to make you up there happy for me and proud of me. I don’t know if I can handle this or not, but I will try,” she wrote online, along with a video of their moments together.

Navalny’s death was met with grief and anger across the world as well as inside Russia, where the smallest acts of political dissent carry huge risks. More than 400 people were detained at makeshift memorials for Navalny across 32 Russian cities, according to OVD-Info.

Navalny returned to Russia in 2021, after spending months recovering in Germany from Novichok poisoning a Bellingcat-CNN investigation found was carried about by Russian intelligence.

He was immediately arrested upon his arrival and spent the rest of his life behind bars on charges he dismissed as politically motivated.

This is a developing story and will be updated.